Remove unused vacuum-truncate-auto injection point

[Sami Imseih]

Hi,

While looking at these injection points I noticed vacuum-truncate-auto
in vacuum_rel() can never fire:

```
    #ifdef USE_INJECTION_POINTS
        if (params.truncate == VACOPTVALUE_AUTO)
            INJECTION_POINT("vacuum-truncate-auto", NULL);
        else if (params.truncate == VACOPTVALUE_DISABLED)
            INJECTION_POINT("vacuum-truncate-disabled", NULL);
        else if (params.truncate == VACOPTVALUE_ENABLED)
            INJECTION_POINT("vacuum-truncate-enabled", NULL);
    #endif
```

truncate is a boolean and can never be VACOPTVALUE_AUTO

```
    Assert(params->truncate != VACOPTVALUE_UNSPECIFIED &&
           params->truncate != VACOPTVALUE_AUTO);
```

This looks like an oversight from 661643dedad, perhaps to mirror
index_cleanup?

```
    if (params.index_cleanup == VACOPTVALUE_AUTO)
        INJECTION_POINT("vacuum-index-cleanup-auto", NULL);
```

Small cleanup attached.

--
Sami Imseih
Amazon Web Services (AWS)

v1-0001-Remove-unused-vacuum-truncate-auto-injection-poin.patch
Description: Binary data